1. Field of the Invention
The present invention relates to a plasma display apparatus, and more particularly, to the structures of electrodes capable of improving efficiencies of sustain discharge and address discharge in discharge cells arranged in delta.
2. Description of the Background Art
In a plasma display apparatus, discharge cells are formed between a rear surface substrate on which barrier ribs are formed and a front surface substrate that faces the rear surface substrate and vacuum ultraviolet (UV) rays generated when inert gases in the discharge cells are discharged by a high frequency voltage emit light from a phosphor to realize an image.
FIG. 1 is a sectional view illustrating a discharge cell of a common plasma display panel (PDP).
First, the discharge cell is formed by a plurality of barrier ribs 24 with which a discharge space is partitioned off on a rear surface substrate 18 that faces a front surface substrate 10. FIG. 1 illustrates that square delta barrier ribs partition off the discharge cell.
A data electrode X is arranged on the rear surface substrate 18 and a scan electrode Y and a sustain electrode Z are arranged on the front surface substrate 10 to make a pair. The rear surface substrate 18 illustrated in FIG. 1 is rotated at 90° so that the data electrode X intersects the other electrodes Y and Z.
A lower dielectric layer 22 for accumulating wall charges is formed on the rear surface substrate 18 where the data electrode X is formed.
The barrier ribs 24 are arranged on the dielectric layer 22 to form a discharge space between the barrier ribs and to prevent the UV rays and visible rays generated by discharge from leaking to adjacent discharge cells. The surfaces of the dielectric layer 22 and the barrier ribs 24 are coated with a phosphor 26.
Since inert gases are implanted into the discharge space, the phosphor 26 is excited by the UV rays generated when the gases are discharged to generate one visible ray among red, green, and blue visible rays.
The scan electrode Y and the sustain electrode Z arranged on the front surface substrate 10 are composed of transparent electrodes 12Y and 12Z and bus electrodes 13Y and 13Z to intersect the data electrode X. Also, a dielectric layer 14 and a protective layer 16 that cover the scan electrode Y and the sustain electrode Z are formed.
After the discharge cell of such a structure is selected by facing discharge between the data electrode X and the scan electrode Y, discharge is sustained by surface discharge between the scan electrode Y and the sustain electrode Z so that the visible rays are emitted.
The scan electrode Y and the sustain electrode Z are composed of the transparent electrodes 12Y and 12Z and the bus electrodes 13Y and 13Z whose width is smaller than the width of the transparent electrodes 12Y and 12Z and each of which is formed at one edge of each of the transparent electrodes 12Y and 12Z.
FIG. 2 is a plan view illustrating conventional square delta barrier ribs before performing an annealing process. FIG. 3 is a plan view illustrating hexagonal delta barrier ribs after performing the annealing process.
The square delta barrier ribs 24 are composed of first barrier ribs 24a that are horizontally formed and second barrier ribs 24b formed in the same direction as the data electrode X. Since the directions in which the square delta barrier ribs 24 are contracted by thermal stress vary at the intersections between the first and second barrier ribs 24a and 24b during the annealing process performed at 550 to 600° C. as illustrated in FIG. 2, the square delta barrier ribs 24 are transformed into hexagonal delta barrier ribs as illustrated in FIG. 3.
The hexagonal delta barrier ribs illustrated in FIG. 3 have advantage in that the area coated with the phosphor increases. However, since the bus electrodes 13Y and 13Z that overlap the first barrier ribs 24a intercept the discharge space to which the visible rays are emitted, emission efficiency and brightness deteriorate.